Vaginal bleeding during intercourse before menstruation may be caused by the following reasons: i. Chronic inflammation such as cervical polyps stimulates the cervical part, and multiple small granulation tissues grow at the mouth of the cervix, and the granulation tissues cause bleeding when touched. Second, endometriosis, coitus in the case of endometriosis to the cervical opening, can also cause vaginal bleeding. Three, uterine fibroids, when fibroids grow under the mucosa and protrude from the cervical opening, the stimulation by external force will cause bleeding. Pelvic inflammatory disease, intercourse with inflammatory disease will not only cause vaginal bleeding, but also aggravate the infection. V. Cervical cancer, the tumor lesions are rich in blood vessels, so it is easy to rupture capillaries after intercourse, causing bleeding. It is recommended to go to hospital for gynecological examination and cervical cancer screening to make a clear diagnosis.